The present invention relates to connectors, and in particular, to a plug and receptacle having at least one mating surface that either converges or diverges.
Connectors for handling substantial amounts of power or current must be designed to make a firm and stable contact to avoid heating that would increase the risk of fire or premature failure.
A known connector pair shown in FIG. 1 has a solid cylindrical prong 10. The back end of the male plug has a cup-shaped terminal 12 with a screw fastener 14 for holding in place a wire 16. A female receptacle 18 has a conical sleeve 20, which is slit to provide a number of petals. These petals diverge inwardly to provide a contact point essentially at the mouth 22 of sleeve 20. The rear of the female receptacle 18 has a socket 24 for holding a wire 26 in place with screw fastener 28. An example of a connector pair of this type is shown in U.S. Pat. No. 4,797,126.
A disadvantage with this type of connector pair is the limited contact surface at mouth 22. Since current must flow at this narrowly defined region, current density becomes quite high, encouraging heating and early failure. Additionally, the narrow region of contact allows prong 10 to rock in the receptacle 18. Also, the arrangement of the screw fasteners restricts the strength of the connection between the wires 16 and 26 to the connector pair.
A known "RCA" plug is shown U.S. Pat. No. 4,789,355. The prong in this plug is split lengthwise, but the two halves of the prong remain parallel and still have the disadvantages described above, that is, a limited contact area and a tendency to rock.
Known banana plugs employ a slender cylindrical shell with spaced, lengthwise slits defining the edges of arching strips that run lengthwise on the plug. This structure is relatively thin and inappropriate for handling high currents. Another disadvantage with a plug of this type is that the arched strips have a peak, which again narrowly limits the contact point to the peak. Because of this limited contact surface, the heating, unreliability and rocking problems discussed above still exist.
In U.S. Pat. No. 4,735,588, a split male plug has a pair of prongs that arch outwardly at their center. These prongs are inserted into a female cavity, whose cross section is constant. Again, the contact surface is limited with the consequential disadvantages noted above. See also U.S. Pat. No. 4,464,009.
Accordingly, there is a need for an improved connector pair that can handle relatively high currents and power levels, with a simple, reliable structure that provides a relatively broad contact area.